Publications by authors named "Andreas Herrmann"

415 Publications

Activation of the Catalytic Activity of Thrombin for Fibrin Formation by Ultrasound.

Angew Chem Int Ed Engl 2021 May 3. Epub 2021 May 3.

DWI - Leibniz Institute for Interactive Materials, Macromolecular Materials and Systems, Forckenbeckstr. 50, 52056, Aachen, GERMANY.

Enzymes catalyze a vast variety of reactions rendering the regulation of their activity a key method to control biological function. In this work, we report two systems enabling the ultrasound-induced activation of thrombin, which is vital for the coagulation cascade of secondary hemostasis. Firstly, we designed polyaptamers, which can specifically bind to thrombin inhibiting its catalytic activity. With both ultrasound generating inertial cavitation (20 kHz) and therapeutic medical focused ultrasound (5 MHz), the specific interactions between polyaptamer and enzyme are cleaved restoring the activity of thrombin to catalyze the conversion of fibrinogen into fibrin. Secondly, we expanded this approach to split aptamers conjugated to the surface of gold nanoparticles (AuNPs). In the presence of thrombin, these assemble into an aptamer tertiary structure, induce AuNP aggregation, and deactivate the enzyme. By ultrasonication, the AuNP aggregates disassemble releasing and activating the enzyme. Notably, the latter process is reversible and can be induced multiple times without apparent fatigue. We envision that this proof-of-concept approach to regulate the activity of aptamer-guarded enzymes by ultrasound will be a blueprint to control the function of other proteins by mechanical stimuli and open further avenues in sonogenetics.
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http://dx.doi.org/10.1002/anie.202105404DOI Listing
May 2021

Genetically Engineered Polypeptide Adhesive Coacervates for Surgical Applications.

Angew Chem Int Ed Engl 2021 Apr 22. Epub 2021 Apr 22.

Tsinghua University, Department of Chemistry, qinghua yuan, 100084, Beijing, CHINA.

Adhesive hydrogels have been developed for wound healing applications. However, their adhesive performance is impaired dramatically due to their high swelling on wet tissues. To tackle this challenge, we fabricated a new type of non-swelling protein adhesive for underwater and in vivo applications. In this soft material, the electrostatic complexation between supercharged polypeptides with oppositely charged surfactants containing 3,4-dihydroxylphenylalanine or azobenzene moieties plays an important role for the formation of ultra-strong adhesive coacervates. Remarkably, the adhesion capability is superior to commercial cyanoacrylate when tested in ambient conditions. Moreover, the adhesion is stronger than other reported protein-based adhesives in underwater environment. The ex vivo and in vivo experiments demonstrate the persistent adhesive performance and outstanding behaviors for wound sealing and healing. Thus, this new type of genetically engineered adhesive coacervates is a very promising alternative for surgical applications.
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http://dx.doi.org/10.1002/anie.202100064DOI Listing
April 2021

An Artificial Phase-Transitional Underwater Bioglue with Robust and Switchable Adhesion Performance.

Angew Chem Int Ed Engl 2021 Mar 1. Epub 2021 Mar 1.

State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.

Complex coacervation enables important wet adhesion processes in natural and artificial systems. However, existed synthetic coacervate adhesives show limited wet adhesion properties, non-thermoresponsiveness, and inferior biodegradability, greatly hampering their translations. Herein, by harnessing supramolecular assembly and rational protein design, we present a temperature-sensitive wet bioadhesive fabricated through recombinant protein and surfactant. Mechanical performance of the bioglue system is actively tunable with thermal triggers. In cold condition, adhesion strength of the bioadhesive was only about 50 kPa. By increasing temperature, the strength presented up to 600 kPa, which is remarkably stronger than other biological counterparts. This is probably due to the thermally triggered phase transition of the engineered protein and the formation of coacervate, thus leading to the enhanced wet adhesion bonding.
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http://dx.doi.org/10.1002/anie.202102158DOI Listing
March 2021

COR-101, ein menschlicher Antikörper gegen COVID-19.

Biospektrum (Heidelb) 2021 12;27(1):46-48. Epub 2021 Feb 12.

Abteilung Biotechnologie, Institut für Biochemie, Biotechnologie und Bioinformatik, Technische Universität Braunschweig, Spielmannstraße 7, D-38106 Braunschweig, Deutschland.

COR-101 is a fully human, Fc silenced IgG that was discovered by antibody phage display. It reduced the SARS-CoV-2 virus load in the lung by more than 99 percent in Hamster models and led to much faster recovery. Its mode of action has been elucidated by solving the atomic structure of its interaction with SARS-CoV-2. The antibody competes with ACE2 binding by blocking a large area of the SARS-CoV-2 spike protein.
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http://dx.doi.org/10.1007/s12268-021-1512-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7880633PMC
February 2021

Improved Treatment Options for Glaucoma with Brimonidine-Loaded Lipid DNA Nanoparticles.

ACS Appl Mater Interfaces 2021 Mar 2;13(8):9445-9456. Epub 2021 Feb 2.

DWI - Leibniz Institute for Interactive Materials, Forckenbeckstrasse 50, Aachen 52056, Germany.

Glaucoma is the second leading cause of irreversible blindness worldwide. Among others, elevated intraocular pressure (IOP) is one of the hallmarks of the disease. Antiglaucoma drugs such as brimonidine can lower the IOP but their adherence to the ocular surface is low, leading to a low drug uptake. This results in a frequent dropping regime causing low compliance by the patients. Lipid DNA nanoparticles (NPs) have the intrinsic ability to bind to the ocular surface and can be loaded with different drugs. Here, we report DNA NPs functionalized for loading of brimonidine through specific aptamers and via hydrophobic interactions with double stranded micelles. Both NP systems exhibited improved affinity toward the cornea and retained release of the drug as compared to controls both in vitro and in vivo. Both NP types were able to lower the IOP in living animals significantly more than pristine brimonidine. Importantly, the brimonidine-loaded NPs showed no toxicity and improved efficacy and hence should improve compliance. In conclusion, this drug-delivery system offers high chances of an improved treatment for glaucoma and thus preserving vision in the aging population.
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http://dx.doi.org/10.1021/acsami.0c18626DOI Listing
March 2021

Mechanochemical bond scission for the activation of drugs.

Nat Chem 2021 02 29;13(2):131-139. Epub 2021 Jan 29.

DWI - Leibniz Institute for Interactive Materials, Aachen, Germany.

Pharmaceutical drug therapy is often hindered by issues caused by poor drug selectivity, including unwanted side effects and drug resistance. Spatial and temporal control over drug activation in response to stimuli is a promising strategy to attenuate and circumvent these problems. Here we use ultrasound to activate drugs from inactive macromolecules or nano-assemblies through the controlled scission of mechanochemically labile covalent bonds and weak non-covalent bonds. We show that a polymer with a disulfide motif at the centre of the main chain releases an alkaloid-based anticancer drug from its β-carbonate linker by a force-induced intramolecular 5-exo-trig cyclization. Second, aminoglycoside antibiotics complexed by a multi-aptamer RNA structure are activated by the mechanochemical opening and scission of the nucleic acid backbone. Lastly, nanoparticle-polymer and nanoparticle-nanoparticle assemblies held together by hydrogen bonds between the peptide antibiotic vancomycin and its complementary peptide target are activated by force-induced scission of hydrogen bonds. This work demonstrates the potential of ultrasound to activate mechanoresponsive prodrug systems.
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http://dx.doi.org/10.1038/s41557-020-00624-8DOI Listing
February 2021

Spontaneous binding of potential COVID-19 drugs (Camostat and Nafamostat) to human serine protease TMPRSS2.

Comput Struct Biotechnol J 2021 28;19:467-476. Epub 2020 Dec 28.

State Key Laboratory of Genetic Engineering, Shanghai Engineering Research Center of Industrial Microorganisms, MOE Engineering Research Center of Gene Technology, School of Life Sciences, Fudan University, Shanghai 200438, China.

Effective treatment or vaccine is not yet available for combating SARS coronavirus 2 (SARS-CoV-2) that caused the COVID-19 pandemic. Recent studies showed that two drugs, Camostat and Nafamostat, might be repurposed to treat COVID-19 by inhibiting human TMPRSS2 required for proteolytic activation of viral spike (S) glycoprotein. However, their molecular mechanisms of pharmacological action remain unclear. Here, we perform molecular dynamics simulations to investigate their native binding sites on TMPRSS2. We revealed that both drugs could spontaneously and stably bind to the TMPRSS2 catalytic center, and thereby inhibit its proteolytic processing of the S protein. Also, we found that Nafamostat is more specific than Camostat for binding to the catalytic center, consistent with reported observation that Nafamostat blocks the SARS-CoV-2 infection at a lower concentration. Thus, this study provides mechanistic insights into the Camostat and Nafamostat inhibition of the SARS-CoV-2 infection, and offers useful information for COVID-19 drug development.
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http://dx.doi.org/10.1016/j.csbj.2020.12.035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7809394PMC
December 2020

Clouding of intraocular silicone oil in the absence of emulsification.

Retin Cases Brief Rep 2021 Jan 18. Epub 2021 Jan 18.

Department of Ophthalmology, University Medical Center Hamburg-Eppendorf (UKE), Germany Department of Polymer Chemistry, Zernike Institute for Advanced Materials, University of Groningen, The Netherlands University Eye Hospital Tübingen, University of Tübingen, Germany Institute for Ophthalmic Research, University of Tübingen, Germany Department of Ophthalmology, Shanghai General Hospital affiliated to Shanghai Jiaotong University, Shanghai, China.

Purpose: To describe intraocular clouding of silicone oil in the absence of emulsification.

Methods: Retrospective observational case series of patients who received silicone oil injections and developed silicone oil discoloration without emulsification after pars plana vitrectomy. Clinical examinations and physicochemical analyses were performed to find out the common cause for the opaque oil.

Results: Thirteen patients developed silicone oil discoloration after pars plana vitrectomy. It could be traced down that all patients had received silicone oil from one respective production batch. The silicone oil was removed as soon as possible after the changes were detected (range, 8-16 weeks). Gas chromatography flame ionization detector (GC-FIC), size exclusion chromatography (SEC) and high performance liquid chromatography (HPLC) analysis showed the absence of small molecular weight compounds in the opaque lot. Thermogravimetric analysis (TGA) revealed the opaque lot was more temperature stable. During the follow-ups, no obvious retinal toxicity could be observed and best recorded visual acuity improved considerably in twelve patients and was only limited by the underlying retinal pathology.

Conclusion: This is the first report on opacification of intraocular silicone oil without emulsification. This discoloration of silicone oil may disturb vision and prevent proper fundus examination, however, seems to be a non-toxic phenomenon without serious long-term consequences.
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http://dx.doi.org/10.1097/ICB.0000000000001123DOI Listing
January 2021

Potent antitumor effects of cell-penetrating peptides targeting STAT3 axis.

JCI Insight 2021 01 25;6(2). Epub 2021 Jan 25.

Department of Immuno-Oncology and.

To date, there are no inhibitors that directly and specifically target activated STAT3 and c-Myc in the clinic. Although peptide-based inhibitors can selectively block activated targets, their clinical usage is limited because of low cell penetration and/or serum stability. Here, we generated cell-penetrating acetylated (acet.) STAT3, c-Myc, and Gp130 targeting peptides by attaching phosphorothioated (PS) polymer backbone to peptides. The cell-penetrating peptides efficiently penetrated cells and inhibited activation of the intended targets and their downstream genes. Locally or systemically treating tumor-bearing mice with PS-acet.-STAT3 peptide at low concentrations effectively blocked STAT3 in vivo, resulting in significant antitumor effects in 2 human xenograft models. Moreover, PS-acet.-STAT3 peptide penetrated and activated splenic CD8+ T cells in vitro. Treating immune-competent mice bearing mouse melanoma with PS-acet.-STAT3 peptide inhibited STAT3 in tumor-infiltrating T cells, downregulating tumor-infiltrating CD4+ T regulatory cells while activating CD8+ T effector cells. Similarly, systemic injections of the cell-penetrating c-Myc and Gp130 peptides prevented pancreatic tumor growth and induced antitumor immune responses. Taken together, we have developed therapeutic peptides that effectively and specifically block challenging cancer targets, resulting in antitumor effects through both direct tumor cell killing and indirectly through antitumor immune responses.
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http://dx.doi.org/10.1172/jci.insight.136176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7934871PMC
January 2021

Aptamer protective groups tolerate different reagents and reactions for regioselective modification of neomycin B.

Org Biomol Chem 2020 Dec 25;18(47):9606-9610. Epub 2020 Nov 25.

DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany.

The aptameric protective group strategy for the one-step regioselective transformation of aminoglycoside antibiotics was found to be compatible with diverse reagents and reaction conditions. New derivatives of neomycin B were synthesized with regioselectivities of >99%. This result extends the scope of applicability of APGs facilitating access to novel aminoglycoside derivatives.
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http://dx.doi.org/10.1039/d0ob02104kDOI Listing
December 2020

Reversibly Photo-Modulating Mechanical Stiffness and Toughness of Bioengineered Protein Fibers.

Angew Chem Int Ed Engl 2021 02 9;60(6):3222-3228. Epub 2020 Dec 9.

Zernike Institute for Advanced Materials, Nijenborgh 4, 9747, AG, Groningen, The Netherlands.

Light-responsive materials have been extensively studied due to the attractive possibility of manipulating their properties with high spatiotemporal control in a non-invasive fashion. This stimulated the development of a series of photo-deformable smart devices. However, it remained a challenge to reversibly modulate the stiffness and toughness of bulk materials. Here, we present bioengineered protein fibers and their optomechanical manipulation by employing electrostatic interactions between supercharged polypeptides (SUPs) and an azobenzene (Azo)-based surfactant. Photo-isomerization of the Azo moiety from the E- to Z-form reversibly triggered the modulation of tensile strength, stiffness, and toughness of the bulk protein fiber. Specifically, the photo-induced rearrangement into the Z-form of Azo possibly strengthened cation-π interactions within the fiber material, resulting in an around twofold increase in the fiber's mechanical performance. The outstanding mechanical and responsive properties open a path towards the development of SUP-Azo fibers as smart stimuli-responsive mechano-biomaterials.
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http://dx.doi.org/10.1002/anie.202012848DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7898284PMC
February 2021

Controlling Optical and Catalytic Activity of Genetically Engineered Proteins by Ultrasound.

Angew Chem Int Ed Engl 2021 01 13;60(3):1493-1497. Epub 2020 Nov 13.

DWI-Leibniz Institute for Interactive Materials, Forckenbeckstrasse 50, 52056, Aachen, Germany.

Ultrasound (US) produces cavitation-induced mechanical forces stretching and breaking polymer chains in solution. This type of polymer mechanochemistry is widely used for synthetic polymers, but not biomacromolecules, even though US is biocompatible and commonly used for medical therapy as well as in vivo imaging. The ability to control protein activity by US would thus be a major stepping-stone for these disciplines. Here, we provide the first examples of selective protein activation and deactivation by means of US. Using GFP as a model system, we engineer US sensitivity into proteins by design. The incorporation of long and highly charged domains enables the efficient transfer of force to the protein structure. We then use this principle to activate the catalytic activity of trypsin by inducing the release of its inhibitor. We expect that this concept to switch "on" and "off" protein activity by US will serve as a blueprint to remotely control other bioactive molecules.
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http://dx.doi.org/10.1002/anie.202010324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7839785PMC
January 2021

DNA hybridization as a general method to enhance the cellular uptake of nanostructures.

Nanoscale 2020 Nov 16;12(41):21299-21305. Epub 2020 Oct 16.

DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany.

The biomedical application of nanoparticles (NPs) for diagnosis and therapy is considerably stalled by their inefficient cellular internalization. Many strategies to overcome this obstacle have been developed but are not generally applicable to different NP systems, consequently underlining the need for a universal method that enhances NP entry into cells. Here we describe a method to increase NP cellular uptake via strand hybridization between DNA-functionalized NPs and cells that bear the respective complementary sequence incorporated into the membrane. By this, the NPs bind efficiently to the cellular surface enhancing internalization of three completely different NP types: DNA tetrahedrons, gold (Au) NPs, and polystyrene (PS) NPs. We show that our approach is a simple and generalizable strategy that can be applied to virtually every functionalizable NP system.
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http://dx.doi.org/10.1039/d0nr02405hDOI Listing
November 2020

Selective flexible packaging pathways of the segmented genome of influenza A virus.

Nat Commun 2020 08 28;11(1):4355. Epub 2020 Aug 28.

Molecular Biophysics, Department for Biology, IRI Life Sciences, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115, Berlin, Germany.

The genome of influenza A viruses (IAV) is encoded in eight distinct viral ribonucleoproteins (vRNPs) that consist of negative sense viral RNA (vRNA) covered by the IAV nucleoprotein. Previous studies strongly support a selective packaging model by which vRNP segments are bundling to an octameric complex, which is integrated into budding virions. However, the pathway(s) generating a complete genome bundle is not known. We here use a multiplexed FISH assay to monitor all eight vRNAs in parallel in human lung epithelial cells. Analysis of 3.9 × 10 spots of colocalizing vRNAs provides quantitative insights into segment composition of vRNP complexes and, thus, implications for bundling routes. The complexes rarely contain multiple copies of a specific segment. The data suggest a selective packaging mechanism with limited flexibility by which vRNPs assemble into a complete IAV genome. We surmise that this flexibility forms an essential basis for the development of reassortant viruses with pandemic potential.
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http://dx.doi.org/10.1038/s41467-020-18108-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7455735PMC
August 2020

De novo rational design of a freestanding, supercharged polypeptide, proton-conducting membrane.

Sci Adv 2020 Jul 17;6(29):eabc0810. Epub 2020 Jul 17.

Macromolecular Chemistry and New Polymeric Materials, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, The Netherlands.

Proton translocation enables important processes in nature and man-made technologies. However, controlling proton conduction and fabrication of devices exploiting biomaterials remains a challenge. Even more difficult is the design of protein-based bulk materials without any functional starting scaffold for further optimization. Here, we show the rational design of proton-conducting, protein materials exceeding reported proteinaceous systems. The carboxylic acid-rich structures were evolved step by step by exploring various sequences from intrinsically disordered coils over supercharged nanobarrels to hierarchically spider β sheet containing protein-supercharged polypeptide chimeras. The latter material is characterized by interconnected β sheet nanodomains decorated on their surface by carboxylic acid groups, forming self-supportive membranes and allowing for proton conduction in the hydrated state. The membranes showed an extraordinary proton conductivity of 18.5 ± 5 mS/cm at RH = 90%, one magnitude higher than other protein devices. This design paradigm offers great potential for bioprotonic device fabrication interfacing artificial and biological systems.
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http://dx.doi.org/10.1126/sciadv.abc0810DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7439445PMC
July 2020

Toward Drug Release Using Polymer Mechanochemical Disulfide Scission.

J Am Chem Soc 2020 08 17;142(34):14725-14732. Epub 2020 Aug 17.

DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany.

Traditional pharmacotherapy suffers from multiple drawbacks that hamper patient treatment, such as the buildup of antibiotic resistances or low drug selectivity and toxicity during systemic application. To overcome these challenges, drug activity can be controlled by employing delivery, targeting, or release solutions that mostly rely on the response to external physicochemical stimuli. Due to various technical limitations, mechanical force as a stimulus in the context of polymer mechanochemistry has so far not been used for this purpose, yet it has been proven to be a convenient and robust method to site-selectively rearrange or cleave bonds with submolecular precision in the realm of materials chemistry. Here, we present an unprecedented mechanochemically responsive system capable of successively releasing small furan-containing molecules, including the furylated fluorophore dansyl and the drugs furosemide as well as furylated doxorubicin, by ultrasound-induced selective scission of disulfide-centered polymers in solution. We show that mechanochemically generated thiol-terminated polymers undergo a Michael-type addition to Diels-Alder (DA) adducts of furylated drugs and acetylenedicarboxylate derivatives, initiating the downstream release of the small molecule drug by a retro DA reaction. We believe that this method can serve as a blueprint for the activation of many other small molecules.
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http://dx.doi.org/10.1021/jacs.0c07077DOI Listing
August 2020

Self-assembled DNA nanoparticles loaded with travoprost for glaucoma-treatment.

Nanomedicine 2020 10 3;29:102260. Epub 2020 Jul 3.

Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands; DWI - Leibniz Institute for Interactive Materials, Aachen, Germany; Institute for Technical and Macromolecular Chemistry, Aachen, Germany. Electronic address:

Lipid DNA nanoparticles (NPs) exhibit an intrinsic affinity to the ocular surface and can be loaded by hybridization with fluorophore-DNA conjugates or with the anti-glaucoma drug travoprost by hybridizing an aptamer that binds the medication. In the travoprost-loaded NPs (Trav-NPs), the drug is bound by specific, non-covalent interactions, not requiring any chemical modification of the active pharmaceutical ingredient. Fluorescently labeled Trav-NPs show a long-lasting adherence to the eye, up to sixty minutes after eye drop instillation. Biosafety of the Trav-NPs was proved and in vivo. Ex vivo and in vivo quantification of travoprost via LC-MS revealed that Trav-NPs deliver at least twice the amount of the drug at every time-point investigated compared to the pristine drug. The data successfully show the applicability of a DNA-based drug delivery system in the field of ophthalmology for the treatment of a major retinal eye disease, i.e. glaucoma.
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http://dx.doi.org/10.1016/j.nano.2020.102260DOI Listing
October 2020

Liquid-Ordered Phase Formation by Mammalian and Yeast Sterols: A Common Feature With Organizational Differences.

Front Cell Dev Biol 2020 12;8:337. Epub 2020 Jun 12.

Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal.

Here, biophysical properties of membranes enriched in three metabolically related sterols are analyzed both and . Unlike cholesterol and ergosterol, the common metabolic precursor zymosterol is unable to induce the formation of a liquid ordered () phase in model lipid membranes and can easily accommodate in a gel phase. As a result, Zym has a marginal ability to modulate the passive membrane permeability of lipid vesicles with different compositions, contrary to cholesterol and ergosterol. Using fluorescence-lifetime imaging microscopy of an aminostyryl dye in living mammalian and yeast cells we established a close parallel between sterol-dependent membrane biophysical properties and . This approach unraveled fundamental differences in yeast and mammalian plasma membrane organization. It is often suggested that, in eukaryotes, areas that are sterol-enriched are also rich in sphingolipids, constituting highly ordered membrane regions. Our results support that while cholesterol is able to interact with saturated lipids, ergosterol seems to interact preferentially with monounsaturated phosphatidylcholines. Taken together, we show that different eukaryotic kingdoms developed unique solutions for the formation of a sterol-rich plasma membrane, a common evolutionary trait that accounts for sterol structural diversity.
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http://dx.doi.org/10.3389/fcell.2020.00337DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7304482PMC
June 2020

Four-Dimensional Deoxyribonucleic Acid-Gold Nanoparticle Assemblies.

Angew Chem Int Ed Engl 2020 09 28;59(39):17250-17255. Epub 2020 Jul 28.

DWI-Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany.

Organization of gold nanoobjects by oligonucleotides has resulted in many three-dimensional colloidal assemblies with diverse size, shape, and complexity; nonetheless, autonomous and temporal control during formation remains challenging. In contrast, living systems temporally and spatially self-regulate formation of functional structures by internally orchestrating assembly and disassembly kinetics of dissipative biomacromolecular networks. We present a novel approach for fabricating four-dimensional gold nanostructures by adding an additional dimension: time. The dissipative character of our system is achieved using exonuclease III digestion of deoxyribonucleic acid (DNA) fuel as an energy-dissipating pathway. Temporal control over amorphous clusters composed of spherical gold nanoparticles (AuNPs) and well-defined core-satellite structures from gold nanorods (AuNRs) and AuNPs is demonstrated. Furthermore, the high specificity of DNA hybridization allowed us to demonstrate selective activation of the evolution of multiple architectures of higher complexity in a single mixture containing small and larger spherical AuNPs and AuNRs.
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http://dx.doi.org/10.1002/anie.202007616DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7540408PMC
September 2020

Quantification of Multivalent Interactions between Sialic Acid and Influenza A Virus Spike Proteins by Single-Molecule Force Spectroscopy.

J Am Chem Soc 2020 07 29;142(28):12181-12192. Epub 2020 Jun 29.

Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany.

Multivalency is a key principle in reinforcing reversible molecular interactions through the formation of multiple bonds. The influenza A virus deploys this strategy to bind strongly to cell surface receptors. We performed single-molecule force spectroscopy (SMFS) to investigate the rupture force required to break individual and multiple bonds formed between synthetic sialic acid (SA) receptors and the two principal spike proteins of the influenza A virus (H3N2): hemagglutinin (H3) and neuraminidase (N2). Kinetic parameters such as the rupture length (χ) and dissociation rate () are extracted using the model by Friddle, De Yoreo, and Noy. We found that a monovalent SA receptor binds to N2 with a significantly higher bond lifetime (270 ms) compared to that for H3 (36 ms). By extending the single-bond rupture analysis to a multibond system of protein-receptor pairs, we provide an unprecedented quantification of the mechanistic features of multivalency between H3 and N2 with SA receptors and show that the stability of the multivalent connection increases with the number of bonds from tens to hundreds of milliseconds. Association rates () are also provided, and an estimation of the dissociation constants () between the SA receptors to both proteins indicate a 17-fold higher binding affinity for the SA-N2 bond with respect to that of SA-H3. An optimal designed multivalent SA receptor showed a higher binding stability to the H3 protein of the influenza A virus than to the monovalent SA receptor. Our study emphasizes the influence of the scaffold on the presentation of receptors during multivalent binding.
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http://dx.doi.org/10.1021/jacs.0c02852DOI Listing
July 2020

Yeast Sphingolipid-Enriched Domains and Membrane Compartments in the Absence of Mannosyldiinositolphosphorylceramide.

Biomolecules 2020 06 6;10(6). Epub 2020 Jun 6.

Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal.

The relevance of mannosyldiinositolphosphorylceramide [M(IP)C] synthesis, the terminal complex sphingolipid class in the yeast , for the lateral organization of the plasma membrane, and in particular for sphingolipid-enriched gel-like domains, was investigated by fluorescence spectroscopy and microscopy. We also addressed how changing the complex sphingolipid profile in the plasma membrane could influence the membrane compartments (MC) containing either the arginine/ H symporter Can1p (MCC) or the proton ATPase Pma1p (MCP). To achieve these goals, wild-type () and Δ cells, which are unable to synthesize M(IP)C accumulating mannosylinositolphosphorylceramide (MIPC), were compared. Living cells, isolated plasma membrane and giant unilamellar vesicles reconstituted from plasma membrane lipids were labelled with various fluorescent membrane probes that report the presence and organization of distinct lipid domains, global order, and dielectric properties. Can1p and Pma1p were tagged with GFP and mRFP, respectively, in both yeast strains, to evaluate their lateral organization using confocal fluorescence intensity and fluorescence lifetime imaging. The results show that deletion strongly affects the rigidity of gel-like domains but not their relative abundance, whereas no significant alterations could be perceived in ergosterolenriched domains. Moreover, in these cells lacking M(IP)C, a clear alteration in Pma1p membrane distribution, but no significant changes in Can1p distribution, were observed. Thus, this work reinforces the notion that sphingolipid-enriched domains distinct from ergosterol-enriched regions are present in the plasma membrane and suggests that M(IP)C is important for a proper hydrophobic chain packing of sphingolipids in the gel-like domains of cells. Furthermore, our results strongly support the involvement of sphingolipid domains in the formation and stability of the MCP, possibly being enriched in this compartment.
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http://dx.doi.org/10.3390/biom10060871DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7356636PMC
June 2020

Next Generation Salivary Lubrication Enhancer Derived from Recombinant Supercharged Polypeptides for Xerostomia.

ACS Appl Mater Interfaces 2020 Aug 21;12(31):34524-34535. Epub 2020 Jul 21.

University Medical Center Groningen, Department of Biomedical Engineering, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.

Insufficient retention of water in adsorbed salivary conditioning films (SCFs) because of altered saliva secretion can lead to oral dryness (xerostomia). Patients with xerostomia sometimes are given artificial saliva, which often lacks efficacy because of the presence of exogenous molecules with limited lubrication properties. Recombinant supercharged polypeptides (SUPs) improve salivary lubrication by enhancing the functionality of endogenously available salivary proteins, which is in stark contrast to administration of exogenous lubrication enhancers. This novel approach is based on establishing a layered architecture enabled by electrostatic bond formation to stabilize and produce robust SCFs in vitro. Here, we first determined the optimal molecular weight of SUPs to achieve the best lubrication performance employing biophysical and in vitro friction measurements. Next, in an ex vivo tongue-enamel friction system, stimulated whole saliva from patients with Sjögren syndrome was tested to transfer this strategy to a preclinical situation. Out of a library of genetically engineered cationic polypeptides, the variant SUP K108cys that contains 108 positive charges and two cysteine residues at each terminus was identified as the best SUP to restore oral lubrication. Employing this SUP, the duration of lubrication (Relief Period) for SCFs from healthy and patient saliva was significantly extended. For patient saliva, the lubrication duration was increased from 3.8 to 21 min with SUP K108cys treatment. Investigation of the tribochemical mechanism revealed that lubrication enhancement is because of the electrostatic stabilization of SCFs and mucin recruitment, which is accompanied by strong water fixation and reduced water evaporation.
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http://dx.doi.org/10.1021/acsami.0c06159DOI Listing
August 2020

Adaptive Flexible Sialylated Nanogels as Highly Potent Influenza A Virus Inhibitors.

Angew Chem Int Ed Engl 2020 07 30;59(30):12417-12422. Epub 2020 Jun 30.

Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195, Berlin, Germany.

Flexible multivalent 3D nanosystems that can deform and adapt onto the virus surface via specific ligand-receptor multivalent interactions can efficiently block virus adhesion onto the cell. We here report on the synthesis of a 250 nm sized flexible sialylated nanogel that adapts onto the influenza A virus (IAV) surface via multivalent binding of its sialic acid (SA) residues with hemagglutinin spike proteins on the virus surface. We could demonstrate that the high flexibility of sialylated nanogel improves IAV inhibition by 400 times as compared to a rigid sialylated nanogel in the hemagglutination inhibition assay. The flexible sialylated nanogel efficiently inhibits the influenza A/X31 (H3N2) infection with IC values in low picomolar concentrations and also blocks the virus entry into MDCK-II cells.
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http://dx.doi.org/10.1002/anie.202006145DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7384064PMC
July 2020

Modular and Versatile Trans-Encoded Genetic Switches.

Angew Chem Int Ed Engl 2020 11 27;59(46):20328-20332. Epub 2020 Jul 27.

Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.

Current bacterial RNA switches suffer from lack of versatile inputs and are difficult to engineer. We present versatile and modular RNA switches that are trans-encoded and based on tRNA-mimicking structures (TMSs). These switches provide a high degree of freedom for reengineering and can thus be designed to accept a wide range of inputs, including RNA, small molecules, and proteins. This powerful approach enables control of the translation of protein expression from plasmid and genome DNA.
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http://dx.doi.org/10.1002/anie.202001372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7689881PMC
November 2020

Macropinocytosis and Clathrin-Dependent Endocytosis Play Pivotal Roles for the Infectious Entry of Puumala Virus.

J Virol 2020 07 1;94(14). Epub 2020 Jul 1.

Department of Molecular Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany

Viruses from the family are encountered as emerging pathogens causing two life-threatening human zoonoses: hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS), with case fatality rates of up to 50%. Here, we comprehensively investigated entry of the Old World hantavirus Puumala virus (PUUV) into mammalian cells, showing that upon treatment with pharmacological inhibitors of macropinocytosis and clathrin-mediated endocytosis, PUUV infections are greatly reduced. We demonstrate that the inhibitors did not interfere with viral replication and that RNA interference, targeting cellular mediators of macropinocytosis, decreases PUUV infection levels significantly. Moreover, we established lipophilic tracer staining of PUUV particles and show colocalization of stained virions and markers of macropinosomes. Finally, we report a significant increase in the fluid-phase uptake of cells infected with PUUV, indicative of a virus-triggered promotion of macropinocytosis. The family comprises a diverse group of virus species and is considered an emerging global public health threat. Individual hantavirus species differ considerably in terms of their pathogenicity but also in their cell biology and host-pathogen interactions. In this study, we focused on the most prevalent pathogenic hantavirus in Europe, Puumala virus (PUUV), and investigated the entry and internalization of PUUV into mammalian cells. We show that both clathrin-mediated endocytosis and macropinocytosis are cellular pathways exploited by the virus to establish productive infections and demonstrate that pharmacological inhibition of macropinocytosis or a targeted knockdown using RNA interference significantly reduced viral infections. We also found indications of an increase of macropinocytic uptake upon PUUV infection, suggesting that the virus triggers specific cellular mechanisms in order to stimulate its own internalization, thus facilitating infection.
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http://dx.doi.org/10.1128/JVI.00184-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7343216PMC
July 2020

Phage capsid nanoparticles with defined ligand arrangement block influenza virus entry.

Nat Nanotechnol 2020 05 30;15(5):373-379. Epub 2020 Mar 30.

Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.

Multivalent interactions at biological interfaces occur frequently in nature and mediate recognition and interactions in essential physiological processes such as cell-to-cell adhesion. Multivalency is also a key principle that allows tight binding between pathogens and host cells during the initial stages of infection. One promising approach to prevent infection is the design of synthetic or semisynthetic multivalent binders that interfere with pathogen adhesion. Here, we present a multivalent binder that is based on a spatially defined arrangement of ligands for the viral spike protein haemagglutinin of the influenza A virus. Complementary experimental and theoretical approaches demonstrate that bacteriophage capsids, which carry host cell haemagglutinin ligands in an arrangement matching the geometry of binding sites of the spike protein, can bind to viruses in a defined multivalent mode. These capsids cover the entire virus envelope, thus preventing its binding to the host cell as visualized by cryo-electron tomography. As a consequence, virus infection can be inhibited in vitro, ex vivo and in vivo. Such highly functionalized capsids present an alternative to strategies that target virus entry by spike-inhibiting antibodies and peptides or that address late steps of the viral replication cycle.
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http://dx.doi.org/10.1038/s41565-020-0660-2DOI Listing
May 2020

Photochemistry of 2-Oxoacetates: from Mechanistic Insights to Profragrances and Bursting Capsules.

Authors:
Andreas Herrmann

Chimia (Aarau) 2020 Feb;74(1):39-48

Firmenich SA, Division Recherche et Développement, Route des Jeunes 1, B. P. 239, CH-1211 Genève 8, Switzerland;, Email:

Photoirradiation of 2-oxoacetates (α-ketoesters) with UV-A light proceeds an intramolecular hydrogen abstraction of the triplet state in a Norrish type II pathway to form carbonyl compounds, carbon monoxide and/or dioxide, and a series of other side products. This review gives a detailed overview of the mechanistic aspects of photooxidation by explaining the pathways that yield the major products formed in the presence or absence of oxygen. Furthermore, it demonstrates how the photoreaction can be used for the light-induced controlled release of fragrances from non-polymeric profragrances, polymer conjugates and core-shell microcapsules in applications of functional perfumery. In the case of microcapsules, the gas formation accompanying the Norrish type II fragmentation can generate an overpressure that expands or cleaves the capsule wall to release fragrances and thus provides access to multi-stimuli responsive delivery systems.
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http://dx.doi.org/10.2533/chimia.2020.39DOI Listing
February 2020

Engineered Near-Infrared Fluorescent Protein Assemblies for Robust Bioimaging and Therapeutic Applications.

Adv Mater 2020 Apr 12;32(17):e2000964. Epub 2020 Mar 12.

State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.

Fluorescent proteins are investigated extensively as markers for the imaging of cells and tissues that are treated by gene transfection. However, limited transfection efficiency and lack of targeting restrict the clinical application of this method rooted in the challenging development of robust fluorescent proteins for in vivo bioimaging. To address this, a new type of near-infrared (NIR) fluorescent protein assemblies manufactured by genetic engineering is presented. Due to the formation of well-defined nanoparticles and spectral operation within the phototherapeutic window, the NIR protein aggregates allow stable and specific tumor imaging via simple exogenous injection. Importantly, in vivo tumor metastases are tracked and this overcomes the limitations of in vivo imaging that can only be implemented relying on the gene transfection of fluorescent proteins. Concomitantly, the efficient loading of hydrophobic drugs into the protein nanoparticles is demonstrated facilitating the therapy of tumors in a mouse model. It is believed that these theranostic NIR fluorescent protein assemblies, hence, show great potential for the in vivo detection and therapy of cancer.
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http://dx.doi.org/10.1002/adma.202000964DOI Listing
April 2020

Phosphorylation-Dependent Differences in CXCR4-LASP1-AKT1 Interaction between Breast Cancer and Chronic Myeloid Leukemia.

Cells 2020 02 14;9(2). Epub 2020 Feb 14.

Klinik für Innere Medizin II, Abteilung für Hämatologie und internistische Onkologie, Universitätsklinikum Jena, Am Klinikum 1, 07747 Jena, Germany.

The serine/threonine protein kinase AKT1 is a downstream target of the chemokine receptor 4 (CXCR4), and both proteins play a central role in the modulation of diverse cellular processes, including proliferation and cell survival. While in chronic myeloid leukemia (CML) the CXCR4 is downregulated, thereby promoting the mobilization of progenitor cells into blood, the receptor is highly expressed in breast cancer cells, favoring the migratory capacity of these cells. Recently, the LIM and SH3 domain protein 1 (LASP1) has been described as a novel CXCR4 binding partner and as a promoter of the PI3K/AKT pathway. In this study, we uncovered a direct binding of LASP1, phosphorylated at S146, to both CXCR4 and AKT1, as shown by immunoprecipitation assays, pull-down experiments, and immunohistochemistry data. In contrast, phosphorylation of LASP1 at Y171 abrogated these interactions, suggesting that both LASP1 phospho-forms interact. Finally, findings demonstrating different phosphorylation patterns of LASP1 in breast cancer and chronic myeloid leukemia may have implications for CXCR4 function and tyrosine kinase inhibitor treatment.
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http://dx.doi.org/10.3390/cells9020444DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7072741PMC
February 2020

Electrostatically PEGylated DNA enables salt-free hybridization in water.

Chem Sci 2019 Nov 12;10(43):10097-10105. Epub 2019 Sep 12.

Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands . Email:

Chemically modified nucleic acids have long served as a very important class of bio-hybrid structures. In particular, the modification with PEG has advanced the scope and performance of oligonucleotides in materials science, catalysis and therapeutics. Most of the applications involving pristine or modified DNA rely on the potential of DNA to form a double-stranded structure. However, a substantial requirement for metal-cations to achieve hybridization has restricted the range of applications. To extend the applicability of DNA in salt-free or low ionic strength aqueous medium, we introduce noncovalent DNA-PEG constructs that allow canonical base-pairing between individually PEGylated complementary strands resulting in a double-stranded structure in salt-free aqueous medium. This method relies on grafting of amino-terminated PEG polymers electrostatically onto the backbone of DNA, which results in the formation of a PEG-envelope. The specific charge interaction of PEG molecules with DNA, absolute absence of metal ions within the PEGylated DNA molecules and formation of a double helix that is significantly more stable than the duplex in an ionic buffer have been unequivocally demonstrated using multiple independent characterization techniques.
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http://dx.doi.org/10.1039/c9sc02598gDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6991176PMC
November 2019